Usually, if a drug can't find much traction with doctors, it gets cast upon big pharma's scrap heap as another failed compound. Not so with cancer drug Iressa, which AstraZeneca (NYSE:AZN) hopes will experience a bit of a renaissance in the coming years, if current clinical studies turn out in its favor.

Last week, the American Society of Clinical Oncology released many of the abstracts for clinical trial data being presented at the conference. Among AstraZeneca's contributions to the medical conference were several early- and mid-stage studies of Iressa in various cancer types, such as breast and lung cancers.

Iressa is already approved in the U.S. as treatment for a sub-population of non-small cell lung cancer patients. It was first approved by the FDA in 2003, but after an ongoing study failed to show an overall survival benefit from the drug in lung cancer patients, Iressa's label was made more restrictive in 2005. Since then, its sales have failed to achieve the heady targets reached by other targeted therapies.

Sales of Iressa were $238 million last year, which was flat compared to 2006. Sales were up 12% year over year in the first quarter of 2008, but that was largely thanks to the falling dollar. The drug’s sales numbers are eclipsed by rival targeted therapies that also treat non-small cell lung cancer (both on- and off-label), including OSI Pharmaceuticals' (NASDAQ:OSIP) Tarceva and ImClone Systems' (NASDAQ:IMCL) Erbitux. Single-quarter sales numbers for both of those drugs outdo Iressa's full-year sales totals.

As the lack of sales growth with Iressa (and some other targeted therapies, like Amgen's (NASDAQ:AMGN) Vectibix) has shown, it's no longer enough for drugmakers to simply get approval for their novel cancer drugs and expect the sales to come flowing in. Not only do these drugs have to overcome FDA and other regulatory hurdles to get approved, but their performance relative to other targeted therapies is equally as important for the future of their sales.

Nothing about the ASCO presentations will likely cause an immediate boost to Iressa's sales levels, but this does show that AstraZeneca clearly isn't giving up on Iressa. Several active studies sponsored by the drugmaker are still recruiting patients on There’s still a chance for AstraZeneca to teach this old drug new tricks.